Since the 7.9-magnitude quake struck Monday, China has dispatched 20 choppers for dropping food and water, transporting the injured and delivering rescuers, Xinhua reported. Thursday's order brings the total to 110.

Rescuers continued their attempts to save those trapped beneath the rubble at schools, businesses and homes.

Aftershocks at times (有時、偶而)forced rescuers to turn away (轉過去)from the fallen buildings, leaving crowds frustrated without knowing the fate of loved ones. Video from one disaster scene shows a woman clinging to a crane after rescuers suspended (暫時終止)a mission at a crumbled building, deeming the site to dangerous to enter.

But there were scattered stories of survival. A 3-year-old girl was rescued from beneath a toppled (倒塌)building in Sichuan's Beichuan County on Thursday, Xinhua said. Photos of the rescue showed the girl sustained (遭受)a leg injury, but was otherwise alert.

A frightened seventh-grade girl was pulled safely from the rubble of a school dormitory Wednesday evening -- 50 hours after she was buried by Monday's earthquake, state-run media said.

In a weak voice, the trapped girl called out (呼喊)to one of the rescuers, "uncle, save me, save me," he said. "If anything (bad) had happened to her, the voice could haunt me for the rest of my life."

More than 4.3 million homes collapsed or sustained damage, according to the Chinese Embassy in Washington, and the official death toll from the quake had reached 14,866 by Wednesday evening. But casualty figures from various cities indicate a higher number of dead.

The state-run Xinhua news agency has provided death tolls for eight communities in Sichuan province that add up to nearly 20,000, including roughly 7,700 who perished in the town of Yingxiu, near the earthquake's epicenter. CNN cannot independently confirm the tallies.

The girl rescued at Muyu Middle School in Sichuan province was among 89 children pulled from the rubble alive. At least 201 students were killed when the building collapsed while many were napping, according to China.org. More than 100 children escaped from the school in Qingchuan County, and rescuers were searching for an unspecified number still believed to be trapped.

Wang Guangfen, a nurse, climbed under a cement slab(厚板) to give the girl, He Cuiqing, medicine, while other rescuers carefully moved slabs until they could remove the girl.

"She appeared very fragile, and there were blood stains on her chest," said China.org, quoting Wang. "But she was still conscious, and called me aunt when I reached her."

Elsewhere in the stricken region, videotape showed a 3-year-old pulled out alive after more than 40 hours in rubble, and a pregnant woman safely rescued, as a small crowd cheered.

In other developments:

Video showed soldiers and relief teams swarmed over mountainsides and piles of debris in and near the epicenter of the quake in Sichuan province, looking for signs of life. Helicopters were flying overhead, some of them dropping food and other supplies.

Hours after 2,000 troops were dispatched to the Zipingpu dam upstream from the earthquake-hit Dujiangyan City, a probe revealed that the dam is stable and safe, Xinhua reported. It was not immediately clear what type of investigation was conducted. State-run media said earlier that the dam on Zipingpu Reservoir had "severe cracks."

Twelve American eco-tourists who were thought to be missing Monday after the quake were able to contact their loved ones by cell phone to let them know they are alive, said an official with World Wildlife Fund, which sponsored the tour. But two Chinese WWF volunteers remain missing.

Fifteen British nationals have been reported missing near the panda preserve. "We have no reports so far of any casualties to British citizens, but we do remain very concerned about reports of some UK citizens being in the affected area," said William Ehrman, British ambassador to China. "We are doing everything that we can to locate them."

More than 30,000 people are "missing or out of reach" in Shifang, Xinhua reported. Citing local government, Xinhua said that the death toll in the city exceeded 2,500. Two chemical plants collapsed, trapping hundreds of people, Xinhua reported Monday. More than 80 tons of of ammonia leaked out, it said. A local official said there were no deaths. The news agency's Wednesday report made no mention of the people it had said were trapped in the chemical plants.

Mianyang has become a massive refugee camp for survivors, Xinhua reported. Thousands of people uprooted around the region are taking shelter downtown at the city's main sports gym and other facilities. Reports say 7,395 people have died and 18,645 are trapped in debris in the city. Among those trapped were about 1,000 students at a middle school.